# KORG iMono/Poly vs ButterSynth

The clearest difference is price: ButterSynth at $19.99 against KORG iMono/Poly's $29.99. ButterSynth also leads on in-app purchases (none vs 1). KORG iMono/Poly's advantage is rating (4.3 vs 4.0) and iOS requirement (9.3 vs 14.0). On review sentiment, ratings volume, update cadence and ads there is nothing between them.

KORG iMono/Poly costs $29.99 and ButterSynth $19.99 up front. KORG iMono/Poly sells 1 one-off in-app purchase. ButterSynth asks for nothing beyond the download.

KORG iMono/Poly holds the better App Store score, 4.3 against 4.0. Both are backed by a comparable volume of ratings — 85 and 63 respectively. Written reviews point the same way: 62% of KORG iMono/Poly's written reviews are positive against 59% of ButterSynth's.

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on November 4, 2026 and November 3, 2026 respectively.

## The numbers

| Metric | KORG iMono/Poly | ButterSynth |
| --- | --- | --- |
| Price | $29.99 | **$19.99** |
| Rating | **[4.3 (85 ratings)](https://appshunter.io/ios/app/korg-imonopoly/id1256218493/reviews)** | [4.0 (63 ratings)](https://appshunter.io/ios/app/buttersynth/id1497419006/reviews) |
| Number of ratings | **85** | 63 |
| Positive reviews | **62.4% of reviews** | 59.2% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 months | Every 2 months |
| Monetization | **Free with in-app purchases** | Paid |
| Size | 203 MB | 468 MB |
| Requires iOS | **9.3** | 14.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [KORG INC.](https://appshunter.io/developer/363714046) | [Arto Vaarala](https://appshunter.io/developer/890886114) |

## What reviewers say

### KORG iMono/Poly

[App page](https://appshunter.io/ios/app/korg-imonopoly/id1256218493)

Experience a classic analog synthesizer reborn on iOS. This app faithfully reproduces the iconic 4VCO sound engine, offering deep sound design capabilities with virtual patches and multi-effects. Seamlessly integrate it into your music production workflow.

**Highlights:** Faithful reproduction of classic 4VCO analog synthesizer, Deep sound design with extensive modulation, Eight virtual patches for expanded sound potential, Two multi-effect units, Quick access to all synth parameters, Integration with KORG Gadget

**Features:** Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Expansion Factory Pack | $4.99 | one-time |

**What reviewers like**

- 🎶 Great sounding synth
- ✨ Fantastic sound quality
- 🎵 Amazing features and sounds
- 💻 Excellent for Gadget integration
- 💡 Versatile for sound design

**What reviewers complain about**

- 🔌 No AUv3 support
- 🚫 Useless without AUv3
- 💸 Waste of money without AUv3
- 📉 Low output volume
- 🤏 Small controls, difficult manipulation

**Reported bugs**

- Cannot restore expansion pack
- Cannot find store tab
- Scale selection broken
- User scale does nothing
- MIDI unstable

**Requested features**

- AUv3 support
- Adaptive Cubasis 3 AUv3
- More iMPC integration
- Transfer patches to desktop VST
- Store preset files on device/flash drive


### ButterSynth

[App page](https://appshunter.io/ios/app/buttersynth/id1497419006)

This powerful synthesizer app offers a hybrid approach, combining wavetable, FM, and sample-based synthesis. Create unique sounds with a vast sonic range, advanced modulation, and a built-in effects rack. It caters to both experienced sound designers and beginners with extensive presets.

**Highlights:** Hybrid 6-oscillator synthesis (wavetable, FM, sample), Built-in wavetable editor, FM engine with 4 operators, Sample and Granulator engines, 32-slot modulation matrix, Internal FX rack with 16 modules, Extensive preset library

**Features:** Vision Pro support

**In-app purchases:** none

**What reviewers like**

- ✨ Deep sound design capabilities
- 🎛️ Versatile modulation matrix
- 🔊 Great sound quality
- 💡 Innovative wavetable generator
- 🌟 Serum-like experience

**What reviewers complain about**

- 📱 Fiddly on small screens
- 🐛 Crashes frequently
- 🐛 Disappears in Cubasis
- 🐛 Spikes CPU usage
- 🐛 Crashes on patch change

**Reported bugs**

- App crashing with AUM
- Disappears in Cubasis randomly
- Crashes all the time inside Logic
- Changing a patch spikes CPU to 99%
- Crashes on every patch change

**Requested features**

- MPE popup possible on top of the auv3
- Button to hide built-in keyboard
- Buffer size option
- Additional MIDI mappings (e.g., arpeggiator toggle)
- Sustain pedal support


## Frequently asked questions

### Is KORG iMono/Poly free?

KORG iMono/Poly costs $29.99, and also offers in-app purchases.

### Is ButterSynth free?

ButterSynth costs $19.99, with no in-app purchases.

### Which has better reviews, KORG iMono/Poly or ButterSynth?

KORG iMono/Poly is rated higher. KORG iMono/Poly averages 4.3 out of 5 from 85 ratings, while ButterSynth averages 4.0 from 63 ratings.

### Do KORG iMono/Poly or ButterSynth have ads?

Neither KORG iMono/Poly nor ButterSynth shows ads.

### Which is updated more often, KORG iMono/Poly or ButterSynth?

KORG iMono/Poly ships an update every 2 months, and ButterSynth every 2 months. Most recently, KORG iMono/Poly was updated on November 4, 2026 and ButterSynth on November 3, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*